Platinum nanosheets synthesized via topotactic reduction of single-layer platinum oxide nanosheets for electrocatalysis.

Increasing the performance of Pt-based electrocatalysts for the oxygen reduction reaction (ORR) is essential for the widespread commercialization of polymer electrolyte fuel cells. Here we show the synthesis of double-layer Pt nanosheets with a thickness of 0.5 nm via the topotactic reduction of 0.9 nm-thick single-layer PtO x nanosheets, which are exfoliated from a layered platinic acid (H y PtO x ). The ORR activity of the Pt nanosheets is two times greater than that of conventionally used state-of-the-art 3 nm-sized Pt nanoparticles, which is attributed to their large electrochemically active surface area (124 m 2  g -1 ). These Pt nanosheets show excellent potential in reducing the amount of Pt used by enhancing its ORR activity. Our results unveil strategies for designing advanced catalysts that are considerably superior to traditional nanoparticle systems, allowing Pt catalysts to operate at their full potential in areas such as fuel cells, rechargeable metal-air batteries, and fine chemical production.